When using power electronics for controlling, e.g., electric motors, power semiconductors comprised in a respective power electronics system are switched at a high frequency in order to map various states of the power electronics system. Due to the switching of the power semiconductors, the power electronics system generates an error signal which can interact in its frequency with other electric devices such as, e.g., a radio receiver as a result of which interfering noises or noise effects can be produced. Particularly in the case of control systems of respective power semiconductors by means of pulse-width modulators, harmonic oscillations frequently occur which act as error signals on other electric devices.
In order to reduce an influence of circuit-related spectral changes of power electronics, methods are described in the prior art in which a timing of a modulator for switching respective power semiconductors of respective power electronics is changed.
In U.S. 2001 0015 904 A1, which is incorporated by reference herein, a method for reducing switching losses when switching power semiconductors of a power electronics system is disclosed. In this context, control signals for respective power semiconductors are determined in dependence on voltages of respective motor phases.
U.S. 2003 0174 081 A1, which is incorporated by reference herein, discloses an inverter with a switching module for controlling respective power semiconductors of the inverter.
In U.S. 2005 0254 265 A1, which is incorporated by reference herein, a method for controlling an output voltage of a voltage converter is found which converts the direct voltage into an output voltage specified by a control unit.
In U.S. 2009 0033 374 A1, which is incorporated by reference herein, a frequency divider and a method for widening the frequency of a spectrum of a current converter in which an additional signal is modulated onto an original clock frequency, is found.
In U.S. Pat. No. 5,901,176 A, which is incorporated by reference herein, a pulse width modulator based on a sigma/delta modulator is disclosed.
In U.S. Pat. No. 6,559,698 B1, which is incorporated by reference herein, a circuit for controlling a clock rate on the basis of a signal provided by an oscillator is disclosed.